1. Field of the Invention
The present invention relates to perpendicular recording heads used in hard disk drives.
2. Background Information
Hard disk drives contain a plurality of magnetic heads that are coupled to rotating disks. The heads can magnetize and sense the magnetic fields of the disks to write and read data, respectively. The heads each have an air bearing surface that cooperates with a flow of air generated by the rotating disks to create an air bearing. The air bearing prevents mechanical wear between the head and the disk.
The heads magnetize the disk in either a horizontal direction parallel with the disk surface, or a vertical direction perpendicular to the surface of the disk. Vertical recording occupies less surface space and thus allows for increased disk capacity. Heads that record in a vertical direction are commonly referred to as perpendicular recording heads (“PMR”).
FIG. 1 illustrates a perpendicular recording head 1 of the prior art. The head 1 includes a main pole 2 and a write shield 3 that are both constructed from magnetic material. The main pole 2 includes a write coil 4. The write coil 4 emanates a magnetic flux 5 when a current flows through the coil 4. The head 1 includes a write-gap layer 6 of non-magnetic material. The write-gap layer 6 induces an outward flow of the magnetic flux 5 into an adjacent disk 7.
To increase the capacity of the disk drive it is desirable to minimize the thickness of the write-gap layer 6. Thin write-gap layers allow backside flux leakage shown by the arrow 8. Backside flux leakage reduces the amount of flux that extends into the disk 7 and reduces the strength of disk magnetization and the resultant read signal. It would be desirable to reduce or eliminate backside flux leakage without significantly varying the fabrication process of the head.